Solid titanium catalyst component, ethylene polymerization catalyst containing the same, and ethylene polymerization process

ABSTRACT

Disclosed is a solid titanium catalyst component which is obtained by a process comprising the steps of bringing (a) a liquid magnesium compound into contact with (b) a liquid titanium compound in the presence of (c) an organosilicon compound having no active hydrogen in an amount of 0.25 to 0.35 mol based on 1 mol of the magnesium compound (a), elevating the temperature of the resulting contact product to a temperature of 105 to 115° C. and maintaining the contact product at this temperature. The contact product may be further brought into contact with not more than 0.5 mol of the organosilicon compound having no active hydrogen (c). Also disclosed are an ethylene polymerization catalyst formed from the solid titanium catalyst component and an organometallic compound and an ethylene polymerization process using the catalyst. By the use of the solid titanium catalyst component, ethylene can be polymerized with high activities and an ethylene polymer having excellent particle properties can be prepared.

FIELD OF THE INVENTION

[0001] The present invention relates to a solid titanium catalystcomponent capable of polymerizing ethylene with high activities andpreparing an ethylene polymer of excellent particle properties, and alsorelates to an ethylene polymerization catalyst containing the solidtitanium catalyst component and an ethylene polymerization process usingthe catalyst.

BACKGROUND OF THE INVENTION

[0002] Ethylene polymers such as homopolyethylene and linear low densitypolyethylene (LLDPE) have been widely used for films, because of theirexcellent transparency and mechanical strength.

[0003] Various processes to prepare the ethylene polymers have beenconventionally proposed, and it is known that the ethylene polymers canbe prepared with high polymerization activities when Ziegler catalystcomprising titanium, magnesium, halogen and optionally an electron donoris used as a polymerization catalyst. It is also known that highactivities are exhibited especially when a solid titanium catalystcomponent obtained from a halogen-containing magnesium compound in aliquid state, a liquid titanium compound and an electron donor is usedas a titanium catalyst component.

[0004] In these processes to prepare ethylene polymers, if ethylene ispolymerized with much higher activities, not only the productivity israised, but also the amount of the catalyst residue per polymer unit,particularly halogen content, is reduced, whereby a problem of moldrusting in the molding process can be solved. Therefore, development ofa titanium catalyst component capable of polymerizing ethylene with muchhigher activities is desired.

[0005] The ethylene polymers obtained immediately after thepolymerization are generally in the form of powder even if thepolymerization is carried out by a slurry polymerization process or agas phase polymerization process, and in this case it is desired thatethylene polymers having good fluidity, containing no finely dividedpowder and having an excellent particle size distribution are produced.The ethylene polymers showing such excellent particle properties havevarious advantages, for example, they can be used as they are dependingon the purpose, even if they are not pelletized.

OBJECT OF THE INVENTION

[0006] The present invention has been made under such circumstances asdescribed above, and it is an object of the invention to provide a solidtitanium catalyst component by which ethylene can be polymerized withhigh activities and an ethylene polymer of excellent particle propertiescan be prepared. It is another object of the invention to provide anethylene polymerization catalyst containing the solid titanium catalystcomponent and an ethylene polymerization process using the catalyst.

SUMMARY OF THE INVENTION

[0007] A solid titanium catalyst component according to the invention isobtained by a process comprising a step of bringing (a) a liquidmagnesium compound into contact with (b) a liquid titanium compound inthe presence of (c) an organosilicon compound having no active hydrogenin an amount of 0.25 to 0.35 mol based on 1 mol of the magnesiumcompound (a) and a step of elevating the temperature of the resultingcontact product (i) to a temperature of 105 to 115° C. and maintainingthe contact product (i) at this temperature, and comprises magnesium,titanium, halogen and the organosilicon compound having no activehydrogen (c).

[0008] A solid titanium catalyst component comprising those ingredientsmentioned above can be obtained also by a process comprising a step ofbringing (a) a liquid magnesium compound into contact with (b) a liquidtitanium compound in the presence of (c) an organosilicon compoundhaving no active hydrogen in an amount of 0.25 to 0.35 mol based on 1mol of the magnesium compound (a) and a step of elevating thetemperature of the resulting contact product (i) to maintain the contactproduct (i) at a given temperature of 105 to 115° C., wherein theorganosilicon compound having no active hydrogen (c) is added in anamount of not more than 0.5 mol based on 1 mol of the magnesium compound(a) while the temperature of the contact product (i) is elevated from atemperature lower by 10° C. than the temperature maintained to atemperature at which the elevation of the temperature is completed, orafter the elevation of the temperature is completed, so as to bring thecompound (c) into contact with the contact product (i).

[0009] An ethylene polymerization catalyst according to the invention isformed from [I] the above-mentioned solid titanium catalyst componentand [II] an organometallic compound.

[0010] In an ethylene polymerization process according to the invention,ethylene is polymerized or ethylene and a comonomer are copolymerized inthe presence of the above-mentioned catalyst.

BRIEF DESCRIPTION OF THE DRAWING

[0011]FIG. 1 shows steps for preparing a solid titanium catalystcomponent according to the invention and shows steps for preparing anethylene polymerization catalyst according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0012] A solid titanium catalyst component, an ethylene polymerizationcatalyst containing the catalyst component and the ethylenepolymerization process according to the invention are described indetail hereinafter.

[0013] The meaning of the term “polymerization” used herein is notlimited to “homopolymerization” but may comprehend “copolymerization”.Also, the meaning of the term “polymer” used herein is not limited to“homopolymer” but may comprehend “copolymer”.

[0014] In FIG. 1, steps for preparing the solid titanium catalystcomponent according to the invention and steps for preparing theethylene polymerization catalyst containing the catalyst component areshown.

[I] Solid Titanium Catalyst Component

[0015] The solid titanium catalyst component according to the inventionis obtained by bringing (a) a liquid magnesium compound, (b) a liquidtitanium compound and (c) an organosilicon compound having no activehydrogen in a specific amount based on 1 mol of the magnesium compound(a) into contact with each other in the manner described later, andcomprises magnesium, titanium, halogen and the organosilicon compoundhaving no active hydrogen (c).

[0016] First, each ingredient used for preparing the solid titaniumcatalyst component of the invention is described below.

(a) Liquid Magnesium Compound

[0017] In the preparation of the solid titanium catalyst component ofthe invention, the magnesium compound is used in a liquid state. Whenthe magnesium compound is solid, it is made liquid prior to use.

[0018] As the magnesium compound, any of (a-1) a magnesium compoundhaving reduction ability and (a-2) a magnesium compound having noreduction ability can be used.

[0019] The magnesium compound having reduction ability (a-1) is, forexample, an organomagnesium compound represented by the followingformula:

X_(n)MgR_(2−n)

[0020] wherein n is a number of 0≦n<2; R is hydrogen, an alkyl group of1 to 20 carbon atoms, an aryl group or a cycloalkyl group; when n is 0,two of R may be the same as or different from each other; and X ishalogen.

[0021] Examples of the organomagnesium compounds having reductionability include:

[0022] dialkylmagnesium compounds, such as dimethylmagnesium,diethylmagnesium, dipropylmagnesium, dibutylmagnesium, diamylmagnesium,dihexylmagnesium, didecylmagnesium, octylbutylmagnesium andethylbutylmagnesium;

[0023] alkylmagnesium halides, such as ethylmagnesium chloride,propylmagnesium chloride, butylmagnesium chloride, hexylmagnesiumchloride and amylmagnesium chloride;

[0024] alkylmagnesium alkoxides, such as butylethoxymagnesium,ethylbutoxymagnesium and octylbutoxymagnesium; and

[0025] other compounds, such as butylmagnesium hydride.

[0026] Examples of the magnesium compounds having no reduction ability(a-2) include:

[0027] magnesium halides, such as magnesium chloride, magnesium bromide,magnesium iodide and magnesium fluoride;

[0028] alkoxymagnesium halides, such as methoxymagnesium chloride,ethoxymagnesium chloride, isopropoxymagnesium chloride, butoxymagnesiumchloride and octoxymagnesium chloride;

[0029] aryloxymagnesium halides, such as phenoxymagnesium chloride andmethylphenoxymagnesium chloride;

[0030] alkoxymagnesiums, such as ethoxymagnesium, isopropoxymagnesium,butoxymagnesium, n-octoxymagnesium and 2-ethylhexoxymagnesium;

[0031] aryloxymagnesiums, such as phenoxymagnesium anddimethylphenoxymagnesium;

[0032] magnesium carboxylates, such as magnesium laurate and magnesiumstearate;

[0033] metallic magnesium; and

[0034] magnesium hydrides.

[0035] The magnesium compounds having no reduction ability (a-2) may becompounds derived from the aforementioned magnesium compounds havingreduction ability (a-1) or compounds derived in the course of theprocess for preparing the catalyst component. For deriving the magnesiumcompounds having no reduction ability (a-2) from the magnesium compoundshaving reduction ability (a-1), for example, the magnesium compoundshaving reduction ability (a-1) are brought into contact with alcohols,ketones, esters, ethers, siloxane compounds, halogen-containingcompounds such as halogen-containing silane compounds,halogen-containing aluminum compounds and acid halides, or compoundshaving OH group or active carbon-to-oxygen bond.

[0036] In the present invention, the magnesium compounds having noreduction ability (a-2) can be derived from the magnesium compoundshaving reduction ability (a-1) using the later-described organosiliconcompound having no active hydrogen (c).

[0037] The magnesium compounds can be used in combination of two or morekinds.

[0038] The magnesium compounds may form complex compounds or doublecompounds together with organometallic compounds of other metals such asaluminum, zinc, boron, beryllium, sodium and potassium (e.g.,later-described organoaluminum compound), or may be mixed with thesemetallic compounds.

[0039] In the preparation of the solid titanium catalyst component [I],other magnesium compounds than the above-mentioned ones are employable,but it is preferred that the magnesium compound is present in the formof a halogen-containing magnesium compound in the finally obtained solidtitanium catalyst component [I]. Therefore, if a magnesium compoundcontaining no halogen is used, the magnesium compound is preferablycontacted with a halogen-containing compound in the course of theprocess to prepare the catalyst component.

[0040] Of the above compounds, the magnesium compounds having noreduction ability, particularly those containing halogen, are preferred.Among them, more preferred are magnesium chloride, alkoxymagnesiumchloride and aryloxymagnesium chloride.

[0041] When the magnesium compound is solid, the solid magnesiumcompound can be made liquid using an electron donor (d-1).

[0042] The electron donor (d-1) includes alcohols, carboxylic acids,aldehydes, amines and metallic acid esters.

[0043] Examples of the alcohols include:

[0044] aliphatic alcohols, such as methanol, ethanol, propanol,isopropyl alcohol, butanol, pentanol, hexanol, 2-methylpentanol,2-ethylbutanol, heptanol, 2-ethylhexanol, octanol, decanol, dodecanol,tetradecyl alcohol, octadecyl alcohol, undecenol, oleyl alcohol, stearylalcohol and ethylene glycol;

[0045] alicyclic alcohols, such as cyclohexanol and methylcyclohexanol;

[0046] aromatic alcohols, such as benzyl alcohol, methylbenzyl alcohol,isopropylbenzyl alcohol, α-methylbenzyl alcohol, α,α-dimethylbenzylalcohol, phenylethyl alcohol, cumyl alcohol, phenol, cresol, xylenol,ethylphenol, propylphenol, nonylphenol and naphthol;

[0047] alkoxy group-containing alcohols, such as n-butyl cellosolve,ethyl cellosolve, 1-butoxy-2-propanol and methylcarbitol; and

[0048] halogen-containing alcohols, such as trichloromethanol,trichloroethanol and trichlorohexanol.

[0049] The carboxylic acids are preferably those having 7 or more carbonatoms, for example, caprylic acid, 2-ethylhexanoic acid, nonylic acidand undecylenic acid.

[0050] The aldehydes are preferably those having 7 or more carbon atoms,for example, caprylaldehyde, 2-ethylhexylaldehyde, undecylaldehyde,benzaldehyde, tolualdehyde and naphthaldehyde.

[0051] The amines are preferably those having 6 or more carbon atoms,for example, heptylamine, octylamine, 2-ethylhexylamine, nonylamine,decylamine, undecylamine and laurylamine.

[0052] Examples of the metallic acid esters include tetraethoxytitanium,tetra-n-propoxytitanium, tetra-i-propoxytitanium, tetrabutoxytitanium,tetrahexoxytitanium, tetrabutoxyzirconium and teraethoxyzirconium. Themetallic acid esters do not include silicic acid esters which aredescribed later as examples of the organosilicon compound having noactive hydrogen (c).

[0053] The electron donors mentioned above can be used in combination oftwo or more kinds, or they can be used in combination with thelater-described other electron donors (d) than the above-mentionedelectron donors.

[0054] Of these, preferred are alcohols and metallic acid esters, andparticularly preferred are alcohols of 6 or more carbon atoms.

[0055] If an electron donor having 6 or more carbon atoms is used as theelectron donor (d-1) in order to make the magnesium compound liquid, theamount thereof is usually not less than 1 mol, preferably 1 to 40 mol,more preferably 1.5 to 12 mol, based on 1 mol of the magnesium compound.If an electron donor having 5 or less carbon atoms is used as theelectron donor (d-1), the amount thereof is usually not less than 15 molbased on 1 mol of the magnesium compound.

[0056] In the contact of the solid magnesium compound and the electrondonor (d-1), a hydrocarbon solvent can be used. Examples of thehydrocarbon solvents include aliphatic hydrocarbons, such as pentane,hexane, heptane, octane, decane, dodecane, tetradecane and kerosine;alicyclic hydrocarbons, such as cyclopentane, methylcyclopentane,cyclohexane, methylcyclohexane, cyclooctane and cyclohexene; aromatichydrocarbons, such as benzene, toluene, xylene, ethylbenzene, cumene andcymene; and halogenated hydrocarbons, such as carbon tetrachloride,dichloroethane, dichloropropane, trichloroethylene and chlorobenzene.

[0057] When the aromatic hydrocarbons are used from among thesesolvents, the alcohol as the electron donor (d-1) is used in the sameamount as defined above in the case of the electron donor of 6 or morecarbon atoms, regardless of the type (number of carbon atoms) of thealcohol used, whereby the magnesium compound can be dissolved. When thealiphatic hydrocarbons and/or the alicyclic hydrocarbons are used, thealcohol as the electron donor (d-1) is used in the above-mentionedamount according to the number of the carbon atoms.

[0058] In the present invention, it is preferred that the solidmagnesium compound is contacted with the electron donor (d-1) in thehydrocarbon solvent.

[0059] In order to dissolve the solid magnesium compound in the electrondonor (d-1), a method of contacting the solid magnesium compound withthe electron donor (d-1), preferably in the presence of the hydrocarbonsolvent, and heating them if necessary is generally adopted. Thiscontact is carried out at a temperature of usually 0 to 300° C.,preferably 20 to 180° C., more preferably 50 to 150° C., for about 15minutes to 5 hours, preferably about 30 minutes to 2 hours.

(b) Liquid Titanium Compound

[0060] In the present invention, a tetravalent titanium compound ispreferably used as the liquid titanium compound. The tetravalenttitanium compound is, for example, a compound represented by thefollowing formula:

Ti(OR)_(g)X_(4−g)

[0061] wherein R is a hydrocarbon group, X is a halogen atom, and 0≦g≦4.

[0062] Examples of such compounds include:

[0063] titanium tetrahalides, such as TiCl₄, TiBr₄ and TiI₄;

[0064] alkoxytitanium trihalides, such as Ti(OCH₃)Cl₃, Ti(OC₂H₅)Cl₃,Ti(On—C₄H₉)Cl₃, Ti(OC₂H₅)Br₃ and Ti(O-iso-C₄H₉)Br₃;

[0065] dialkoxytitanium dihalides, such as Ti(OCH₃)₂Cl₂, Ti(OC₂H₅)₂Cl₂,Ti(On—C₄H₉)₂Cl₂ and Ti (OC₂H₅)₂Br₂;

[0066] trialkoxytitanium monohalides, such as Ti(OCH₃)₃Cl, Ti(OC₂H₅)₃Cl,Ti(On—C₄H₉)₃Cl and Ti(OC₂H₅)₃Br; and

[0067] tetraalkoxytitaniums, such as Ti(OCH₃)₄, Ti(OC₂H₅)₄,Ti(On—C₄H₉)₄, Ti(O-iso-C₄H₉)₄ and Ti(O-2-ethylhexyl)₄.

[0068] Of these, preferred are titanium tetrahalides, and particularlypreferred is titanium tetrachloride. These titanium compounds can beused in combination of two or more kinds. Further, these titaniumcompounds may be diluted with the above-exemplified hydrocarbon solventswhich are used for making the magnesium compound (a) liquid.

(c) Organosilicon Compound Having No Active Hydrogen

[0069] The organosilicon compound having no active hydrogen, which isused in the invention, is represented by, for example, the formula R¹_(x)R² _(y)Si(OR³)_(z) (R¹ and R² are each independently a hydrocarbongroup or halogen, R³ is a hydrocarbon group, 0≦x<2, 0≦y<2, and 0<z≦4).

[0070] Examples of the organosilicon compounds represented by the aboveformula include:

[0071] tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane,tetrabutoxysilane, tetrakis(2-ethylhexyloxy)silane,

[0072] ethyltrimethoxysilane, ethyltriethoxysilane,vinyltrimethoxysilane, methyltrimethoxysilane, n-propyltriethoxysilane,decyltrimethoxysilane, cyclopentyltrimethoxysilane,2-methylcyclopentyltrimethoxysilane,2,3-dimethylcyclopentyltrimethoxysilane, cyclohexyltrimethoxysilane,2-norbornanetrimethoxysilane, 2-norbornanemethyldimethoxysilane,phenyltrimethoxysilane, γ-chloropropyltrimethoxysilane,methyltriethoxysilane, ethyltriethoxysilane, vinyltriethoxysilane,t-butyltriethoxysilane, n-butyltriethoxysilane,iso-butyltriethoxysilane, decyltriethoxysilane,cyclopentyltriethoxysilane, cyclohexyltriethoxysilane,2-norbornanetriethoxysilane, phenyltriethoxysilane,γ-aminopropyltriethoxysilane, chlorotriethoxysilane,ethyltriisopropoxysilane, vinyltributoxysilane, trimethylphenoxysilane,methyltriallyloxysilane, vinyltris(β-methoxyethoxysilane),vinyltriacetoxysilane,

[0073] dimethyldimethoxysilane, diisopropyldimethoxysilane,t-butylmethyldimethoxysilane, dicyclopentyldimethoxysilane,bis(2-methylcyclopentyl)dimethoxysilane,bis(2,3-dimethylcyclopentyl)dimethoxysilane,dicyclohexyldimethoxysilane, cyclohexylmethyldimethoxysilane,diphenyldimethoxysilane, phenylmethyldimethoxysilane,bis-o-tolyldimethoxysilane, bis-m-tolyldimethoxysilane,bis-p-tolyldimethoxysilane, bisethylphenyldimethoxysilane,dimethyldiethoxysilane, t-butylmethyldiethoxysilane,t-amylmethyldiethoxysilane, dicyclopentyldiethoxysilane,diphenyldiethoxysilane, bis-p-tolyldiethoxysilane,cyclohexylmethyldiethoxysilane,

[0074] trimethylmethoxysilane, trimethylethoxysilane,tricyclopentylmethoxysilane, tricyclopentylethoxysilane,dicyclopentylmethylmethoxysilane, dicyclopentylethylmethoxysilane,hexenyltrimethoxysilane, cyclopentyldimethylmethoxysilane,cyclopentyldiethylmethoxysilane, dicylopentylmethylethoxysilane,cyclopentyldimethylethoxysilane and dimethyltetraethoxydisiloxane.

[0075] Of these, preferably used are tetramethoxysilane,tetraethoxysilane and cyclohexylmethyldimethoxysilane. From theviewpoint of catalytic activity, tetraethoxysilane is particularlypreferably used.

[0076] In the present invention, it is enough that the organosiliconcompound having no active hydrogen (c) is contained in the finallyobtained solid titanium catalyst component. In the preparation of thesolid titanium catalyst component, therefore, the organosilicon compoundhaving no active hydrogen (c) itself may not be used, and there can beused compounds capable of producing the organosilicon compound having noactive hydrogen in the course of the process for preparing the solidtitanium catalyst component.

(d) Other Electron Donor

[0077] In the preparation of the solid titanium catalyst component ofthe invention, an electron donor having no active hydrogen (d) may beoptionally used in addition to the organosilicon compound having noactive hydrogen (c).

[0078] Examples of such electron donors (d) include organic acid esters,organic acid halides, organic acid anhydrides, ethers, ketones, tertiaryamines, phosphorous acid esters, phosphoric acid esters, carboxylic acidamides, nitriles, aliphatic carbonates and pyridines. More specifically,there can be mentioned:

[0079] organic acid esters having 2 to 18 carbon atoms, such as methylformate, methyl acetate, ethyl acetate, vinyl acetate, propyl acetate,i-butyl acetate, t-butyl acetate, octyl acetate, cyclohexyl acetate,methyl chloroacetate, ethyl dichloroacetate, ethyl propionate, ethylpyruvate, ethyl pivalate, methyl butyrate, ethyl valerate, methylmethacrylate, ethyl crotonate, ethyl cyclohexanecarboxylate, methylbenzoate, ethyl benzoate, propyl benzoate, butyl benzoate, octylbenzoate, cyclohexyl benzoate, phenyl benzoate, benzyl benzoate, methyltoluate, ethyl toluate, amyl toluate, ethyl ethylbenzoate, methylanisate, ethyl anisate and ethyl ethoxybenzoate;

[0080] acid halides having 2 to 15 carbon atoms, such as acetylchloride, benzoyl chloride and toluyl chloride;

[0081] acid anhydrides, such as acetic anhydride, phthalic anhydride,maleic anhydride, benzoic anhydride, trimellitic anhydride andtetrahydrophthalic anhydride;

[0082] ethers having 2 to 20 carbon atoms, such as methyl ether, ethylether, isopropyl ether, butyl ether, amyl ether, tetrahydrofuran, ethylbenzyl ether, ethylene glycol dibutyl ether, anisole and diphenyl ether;

[0083] ketones having 3 to 20 carbon atoms, such as acetone, methylethyl ketone, methyl isobutyl ketone, ethyl n-butyl ketone,acetophenone, benzophenone, benzoquinone and cyclohexanone;

[0084] tertiary amines, such as trimethylamine, triethylamine,tributylamine, tribenzylamine and tetramethylethylenediamine;

[0085] phosphorous acid esters, such as trimethyl phosphite, triethylphosphite, tri-n-propyl phosphite, triisopropyl phosphite, tri-n-butylphosphite, triisobutyl phosphite, diethyl-n-butyl phosphite anddiethylphenyl phosphite;

[0086] phosphoric acid esters, such as trimethyl phosphate, triphenylphosphate and tritolyl phosphate;

[0087] acid amides, such as N,N-dimethylacetamide, N,N-diethylbenzamideand N,N-dimethyltoluamide;

[0088] nitriles, such as acetonitrile, benzonitrile and tolunitrile;

[0089] aliphatic carbonates, such as dimethyl carbonate, diethylcarbonate and ethylene carbonate; and

[0090] pyridines, such as pyridine, methylpyridine, ethylpyridine anddimethylpyridine.

[0091] These compounds can be used in combination of two or more kinds.

Preparation of Solid Titanium Catalyst Component

[0092] In the present invention, the solid titanium catalyst component[I] can be prepared from the above ingredients by the followingprocesses.

[0093] (1) The liquid magnesium compound (a) and the liquid titaniumcompound (b) are contacted in the presence of the organosilicon compoundhaving no active hydrogen (c) (referred to simply as “organosiliconcompound (c)” hereinafter) in an amount of 0.25 to 0.35 mol based on 1mol of the magnesium compound (a). Then, the temperature of theresulting contact product (i) is elevated to a temperature of 105 to115° C. and maintained at this temperature.

[0094] (2) The temperature of the contact product (i) obtained above iselevated to maintain the contact product (i) at a temperature of 105 to115° C., and in this step, the organosilicon compound (c) is added in anamount of not more than 0.5 mol based on 1 mol of the magnesium compound(a) while the temperature of the contact product (i) is elevated from atemperature lower by 10° C. than the temperature maintained to atemperature at which the elevation of the temperature is completed, orafter the elevation of the temperature is completed, so as to contactthe organosilicon compound (c) with the contact product (i).

[0095] Of the above processes, the process (2) is preferred from theviewpoint of catalytic activity of the resulting solid titanium catalystcomponent.

[0096] According to the invention, in the contact of the components, theorganosilicon compound (c) is used in a specific amount based on themagnesium compound (a).

[0097] It is preferred that the titanium compound (b) is used in such asufficient amount that a solid can be precipitated by the contact evenif any special precipitating means is not adopted. The amount of thetitanium compound (b) used varies depending on the kind thereof, contactconditions, the amount of the organosilicon compound (c), etc., but itis usually not less than 1 mol, preferably about 5 to 200 mol, morepreferably about 10 to 100 mol, based on 1 mol of the magnesium compound(a). Further, the titanium compound (b) is used in an amount ofpreferably more than 1 mol, more preferably not less than 5 mol, basedon 1 mol of the organosilicon compound (c).

[0098] The above processes are described below in more detail.

[0099] The liquid magnesium compound (a) and/or the titanium compound(b), which are to be contacted with each other, may preliminarilycontain the organosilicon compound (c). In this case, theorganomagnesium compound (c) may not be added in the contact step of themagnesium compound (a) and the titanium compound (b), but it may beadded. In any case, the total amount of the organosilicon compound (c)based on the magnesium compound (a) is within the above range.

[0100] In the present invention, the contact of the liquid magnesiumcompound (a) and the liquid titanium compound (b) is carried out at sucha low temperature that a solid is not rapidly produced by the contact.Specifically, the contact is desirably carried out at a temperature of−70 to +50° C., preferably −50 to +30° C., more preferably −40 to +20°C. The temperatures of each solutions used for the contact may bedifferent from each other. If the contact temperature is too low toprecipitate a solid in a contact product (i) in the beginning of thecontact, the contact at the low temperature can be carried out for along period of time to precipitate a solid.

[0101] The temperature of the contact product (i) obtained above is thenslowly elevated to a temperature of 105 to 115° C. so as to precipitatea solid gradually, followed by maintaining this temperature.

[0102] The time for maintaining the temperature is in the range ofusually 0.5 to 6 hours, preferably 1 to 4 hours.

[0103] The time required for elevating the temperature greatly variesdepending on the scale of the reactor, etc.

[0104] When the liquid magnesium compound (a) and the liquid titaniumcompound (b) are contacted under the above conditions in the presence ofthe organosilicon compound having no active hydrogen (c), a granular orspherical solid titanium catalyst component having relatively largeparticle diameters and an excellent particle size distribution can beobtained. When ethylene is subjected to slurry polymerization using thesolid titanium catalyst component of such excellent particle properties,a granular or spherical ethylene polymer having an excellent particlesize distribution, a high bulk density and good fluidity can beobtained.

[0105] According to the process (2), in the step of the process (1)wherein the temperature of the contact product (i) is elevated to atemperature of 105 to 115° C. and maintained at this temperature forusually 0.5 to 6 hours, preferably 1 to 4 hours, the organosiliconcompound (c) is added in an amount of not more than 0.5 mol based on 1mol of the magnesium compound (a) while the temperature of the contactproduct (i) is elevated from a temperature lower by 10° C. than thetemperature maintained to a temperature at which the elevation of thetemperature is completed, or after (preferably, immediately after) theelevation of the temperature is completed, so as to contact theorganosilicon compound (c) with the contact product (i).

[0106] The solid titanium catalyst component of the invention preparedby the above processes comprises magnesium, titanium, halogen and theorganosilicon compound having no active hydrogen (c).

[0107] In the solid titanium catalyst component, it is desired that:

[0108] a magnesium/titanium ratio (by atom) is in the range of about 2to 100, preferably about 4 to 50, more preferably about 5 to 30;

[0109] a halogen/titanium ratio (by atom) is in the range of about 4 to100, preferably about 5 to 90, more preferably about 8 to 50;

[0110] an organosilicon compound (c)/titanium ratio (by mol) is in therange of about 0.01 to 100, preferably about 0.2 to 10, more preferablyabout 0.4 to 6; and

[0111] an organosilicon compound (c)/magnesium ratio (by mol) is in therange of about 0.001 to 0.1, preferably about 0.002 to 0.08, morepreferably about 0.005 to 0.05.

[0112] The solid titanium catalyst component may further contain otheringredients than the above-mentioned ones, e.g., carrier, andspecifically, the other ingredients may be contained in amounts of notmore than 50% by weight, preferably not more than 40% by weight, morepreferably not more than 30% by weight, particularly preferably not morethan 20% by weight.

[0113] The composition of the solid titanium catalyst component can bemeasured by, for example, ICP (atomic absorption spectrometry) or gaschromatography, after the catalyst component is sufficiently washed witha large amount of hexane and dried at room temperature and 0.1 to 1 Torrfor not shorter than 2 hours.

[0114] The solid titanium catalyst component of the invention isdesirably in a granular or spherical shape, and its specific surfacearea is desirably not less than 10 m²/g, preferably about 100 to 1,000m²/g.

[0115] In the present invention, the solid titanium catalyst componentis generally washed with a hydrocarbon solvent prior to use.

Ethylene Polymerization Catalyst

[0116] The ethylene polymerization catalyst according to the inventionis formed from:

[0117] [I] the solid titanium catalyst component, and

[0118] [II] an organometallic component.

[0119] The organometallic compound used in the invention is preferablyan organometallic compound containing a metal selected from Group I toGroup III of the periodic table. Examples of such compounds include anorganoaluminum compound, an alkyl complex compound of Group I metal andaluminum, and an organometallic compound of Group II metal.

[0120] The organoaluminum compound is, for example, a compoundrepresented by the following formula:

R^(a) _(n)AlX_(3−n)

[0121] wherein R^(a) is a hydrocarbon group of 1 to 12 carbon atoms, Xis halogen or hydrogen, and n is 1 to 3.

[0122] R^(a) is a hydrocarbon group of 1 to 12 carbon atoms, e.g., analkyl group, a cycloalkyl group or an aryl group. Particular examplesthereof include methyl, ethyl, n-propyl, isopropyl, isobutyl, pentyl,hexyl, octyl, cyclopentyl, cyclohexyl, phenyl and tolyl.

[0123] Examples of such organoaluminum compounds include:

[0124] trialkylaluminums, such as trimethylaluminum, triethylaluminum,triisopropylaluminum, triisobutylaluminum, trioctylaluminum andtri-2-ethylhexylaluminum;

[0125] alkenylaluminums, such as isoprenylaluminum;

[0126] dialkylaluminum halides, such as dimethylaluminum chloride,diethylaluminum chloride, diisopropylaluminum chloride,diisobutylaluminum chloride and dimethylaluminum bromide;

[0127] alkylaluminum sesquihalides, such as methylaluminumsesquichoride, ethylaluminum sesquichloride, isopropylaluminumsesquichloride, butylaluminum sesquichloride and ethylaluminumsesquibromide;

[0128] alkylaluminum dihalides, such as methylaluminum dichlioride,ethylaluminum dichloride, isopropylaluminum dichloride and ethylaluminumdibromide; and

[0129] alkylaluminum hydrides, such as diethylaluminum hydride anddiisobutylaluminum hydride.

[0130] Also employable as the organoaluminum compound is a compoundrepresented by the following formula:

R^(a) _(n)AlY_(3−n)

[0131] wherein R^(a) is the same as above; Y is —OR^(b) group, —OSiR_(c)₃ group, —OAlR^(d) ₂ group, —NR^(e) ₂ group, —SiR^(f) ₃ group or—N(R^(g))AlR^(h) ₂ group; n is 1 to 2; R^(b), R^(c), R^(d) and R^(h) areeach methyl, ethyl, isopropyl, isobutyl, cyclohexyl, phenyl or the like;R^(e) is hydrogen, methyl, ethyl, isopropyl, phenyl, trimethylsilyl orthe like; and R^(f) and R^(g) are each methyl, ethyl or the like.

[0132] Examples of such organoaluminum compounds include:

[0133] (i) compounds of the formula R^(a) _(n)Al(OR^(b))_(3−n), e.g.,dimethylaluminum methoxide, diethylaluminum ethoxide anddiisobutylaluminum methoxide;

[0134] (ii) compounds of the formula R^(a) _(n)Al(OSiR^(c))_(3−n), e.g.,Et₂Al(OSiMe₃), (iso-Bu)₂Al(OSiMe₃) and (iso-Bu)₂Al(OSiEt₃);

[0135] (iii) compounds of the formula R^(a) _(n)Al(OAlR^(d) ₂)_(3−n),e.g., Et₂AlOAlEt₂ and (iso-Bu)₂AlOAl(iso-Bu)₂;

[0136] (iv) compounds of the formula R^(a) _(n)Al(NR^(e)2)_(3−n), e.g.,Me₂AlNEt₂, Et₂AlNHMe, Me₂AlNHEt, Et₂AlN(Me₃Si)₂ and(iso-Bu)₂AlN(Me₃Si)₂;

[0137] (v) compounds of the formula R^(a) _(n)Al(SiR^(f) ₃)_(3−n), e.g.,(iso-Bu)₂AlSiMe₃; and

[0138] (vi) compounds of the formula R^(a) _(n)Al[N(R^(g))-AlR^(h)₂]_(3−n), e.g., Et₂AlN(Me)-AlEt₂ and (iso-Bu)₂AlN(Et)Al(iso-Bu)₂.

[0139] Further, compounds analogous to the above compounds, for example,organoaluminum compounds wherein two or more aluminum atoms are linkedthrough an oxygen atom or a nitrogen atom, are also employable. Examplesof such compounds include (C₂H₅)₂AlOAl (C₂H₅)₂, (C₄H₉)₂AlOAl (C₄H₉)₂ and(C₂H₅)₂AlN(C₂H₅)Al(C₂H₅)₂.

[0140] Furthermore, aluminoxanes such as methylaluminoxane are alsoemployable.

[0141] The alkyl complex compound of Group I metal and aluminum is, forexample, a compound represented by the following formula:

M¹AlR^(j) ₄

[0142] wherein M¹ is Li, Na or K, and R^(j) is a hydrocarbon group of 1to 15 carbon atoms.

[0143] Examples of such compounds include LiAl(C₂H₅)₄ and LiAl(C₇H₁₅)₄.

[0144] The organometallic compound of Group II metal is, for example, acompound represented by the following formula:

R^(k)R¹M²

[0145] wherein R^(k) and R¹ are each a hydrocarbon group of 1 to 15carbon atoms or halogen, R^(k) and R¹ may be the same as or differentfrom each other with the exception that both of them are halogens, andM² is Mg, Zn or Cd.

[0146] Examples of such compounds include diethylzinc, diethylmagnesium,butylethylmagnesium, ethylmagnesium chloride and butylmagnesiumchloride.

[0147] Of the organoaluminum compounds mentioned above, preferably usedare compounds of the formulas R^(a) ₃AlX_(3−n), R^(a)_(n)Al(OR^(b))_(3−n) and R^(a) _(n)Al(OAlR^(d) ₂)_(3−n), particularlytrialkylaluminums.

[0148] The above compounds can be used in combination of two or morekinds.

[0149] Olefins may be prepolymerized onto the ethylene polymerizationcatalyst of the invention.

[0150] The ethylene polymerization catalyst of the invention may furthercontain other components useful for polymerization of ethylene, inaddition to the above-mentioned components.

Ethylene Polymerization Process

[0151] In the ethylene polymerization process according to theinvention, ethylene is polymerized in the presence of the ethylenepolymerization catalyst comprising the solid titanium catalyst component[I] and the organometallic compound [II], but ethylene may becopolymerized with a small amount of other olefins.

[0152] Examples of the olefins include α-olefins of 3 to 20 carbonatoms, such as propylene, 1-butene, 1-pentene, 1-hexene,3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene,4-methyl-1-pentene, 4,4-dimethyl-1-pentene, 4-methyl-1-hexene,4,4-dimethyl-1-hexene, 4-ethyl-1-hexene, 3-ethyl-1-hexene, 1-octene,1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene and1-eicosene. Further, vinyl compounds, other unsaturated compounds andpolyene compounds are also copolymerizable. For example, there can bementioned:

[0153] aromatic vinyl compounds, such as styrene, substituted styrenes,allylbenzene, substituted allylbenzenes, vinylnaphthalenes, substitutedvinylnaphthalenes, allylnaphthalenes and substituted allylnaphthalenes;

[0154] alicyclic vinyl compounds, such as vinylcyclopentane, substitutedvinylcyclopentanes, vinylcyclohexane, substituted vinylcyclohexanes,vinylcycloheptane, substituted vinylcycloheptanes and allylnorbornane;

[0155] cycloolefins, such as cyclopentene, cycloheptene, norbornene,5-methyl-2-norbornene, tetracyclododecene and2-methyl-1,4,5,8-dimethano-1,2,3,4,4a,5,8,8a-octahydronaphthalene; and

[0156] unsaturated silane compounds, such as allyltrimethylsilane,allyltriethylsilane, 4-trimethylsilyl-1-butene,6-trimethylsilyl-1-hexene, 8-trimethylsilyl-1-octene and10-trimethylsilyl-1-decene.

[0157] Two or more kinds of the above copolymerizable monomers can becopolymerized with ethylene.

[0158] In the ethylene polymerization process of the invention, it isdesired that the solid titanium catalyst component [I] is used in anamount of usually about 0.0001 to 1.0 mmol in terms of the titaniumatom, based on 1 liter of the polymerization volume, and theorganometallic compound [II] is used in such an amount that the amountof the metallic atom in the compound [II] becomes usually about 1 to2,000 mol, preferably about 5 to 500 mol, based on 1 mol of the titaniumatom in the polymerization system.

[0159] The polymerization can be carried out as a liquid phasepolymerization such as solution polymerization or suspensionpolymerization, or as a gas phase polymerization.

[0160] When a slurry polymerization is used, a polymerization-inactiveorganic solvent is generally used as a polymerization solvent. Examplesof the organic solvents include aliphatic hydrocarbons, such as propane,butane, pentane, hexane, heptane, octane, decane, dodecane and kerosine;alicyclic hydrocarbons, such as cyclopentane, cyclohexane andmethylcyclopentane; aromatic hydrocarbons, such as benzene, toluene andxylene; and halogenated hydrocarbons, such as ethylene chloride andchlorobenzene. These solvents may be used in combination. Together withthe organic solvent, a copolymerizable monomer which is liquid at thereaction temperature is also employable.

[0161] The polymerization conditions vary depending on the type ofpolymerization, the kind of the resulting ethylene polymer, etc., butthe polymerization is carried out at a temperature of usually about 20to 300° C., preferably about 50 to 150° C., under a pressure of usuallyatmospheric pressure to 100 kg/cm², preferably about 2 to 50 kg/cm².

[0162] If hydrogen is used in the polymerization process, a molecularweight of the resulting polymer can be modified.

[0163] The polymerization can be carried out batchwise,semi-continuously or continuously. Further, the polymerization can becarried out in two or more stages under different reaction conditions.

[0164] According to invention, in the polymerization of ethylene, acatalyst is formed using the above-described specific solid titaniumcatalyst component, and therefore an ethylene polymer having excellentparticle properties can be prepared with prominently high polymerizationactivities. In the resulting ethylene polymer, accordingly, the amountof catalyst residue per polymer unit, particularly halogen content, issmall, and hence rusting of mold hardly takes place in the moldingprocess. In addition, an ethylene polymer having a low content of finelydivided powder and showing excellent particle properties is obtained,whereby the polymer can be used without being pelletized.

[0165] The ethylene polymer obtained by the present invention desirablyhas a bulk specific gravity of 0.20 to 0.60 g/cc, preferably 0.25 to0.60 g/cc.

[0166] The ethylene polymer desirably has a melt flow rate (MFR,measured in accordance with ASTM D 1238E, 190° C.) of 0.01 to 5,000 g/10min.

[0167] To the ethylene polymer obtained by the invention, additives suchas heat stabilizer, weathering stabilizer, antistatic agent,anti-blocking agent, lubricant, nucleating agent, pigment, dye andinorganic or organic filler can be optionally added.

EFFECT OF THE INVENTION

[0168] According to the present invention, a solid titanium catalystcomponent by which an ethylene polymer having a low content of finelydivided powder and showing excellent particle properties can be producedin an extremely high yield per catalyst unit, an ethylene polymerizationcatalyst containing the solid titanium catalyst component and anethylene polymerization process using the catalyst are provided.

EXAMPLE

[0169] The present invention will be further described with reference tothe following examples, but it should be construed that the invention isin no way limited to those examples.

[0170] In the following examples, composition, particle size and bulkdensity of the solid titanium catalyst component were measured by themethods described below.

[0171] (1) Mg Content, Ti Content

[0172] ICP analysis (ICPF 1000TR, manufactured by Shimazu SeisakushoK.K.)

[0173] (2) Cl Content

[0174] The Cl content was measured by a silver nitrate titration method.

[0175] (3) OR Group Content

[0176] A catalyst sufficiently dried was added to an acetone solutioncontaining 10% by weight of water, and ROH obtained by hydrolysis wasquantitatively determined by gas chromatography.

[0177] (4) Particle Size Distribution

[0178] The particle size distribution was measured by means of avibrating machine (low-tap type, manufactured by Iida Seisakusho K.K.)and a sieve (inner diameter: 200 mm, available from Bunsei Furui K.K.).

[0179] (5) Bulk Specific Gravity

[0180] The bulk specific gravity was measured in accordance with JIS K6721.

Example 1 Preparation of Solid Titanium Catalyst Component

[0181] 4.76 Grams (50 mmol) of anhydrous magnesium chloride, 28.1 ml ofdecane and 16.3 g (125 mmol) of 2-ethylhexyl alcohol were reacted witheach other under heating at 130° C. for 3 hours, to give a homogeneoussolution. To the solution, 3.1 g (15 mmol) of tetraethoxysilane wasadded, and they were stirred at 50° C. for 2 hours to dissolvetetraethoxysilane in the solution.

[0182] The whole amount of the homogeneous solution obtained above wascooled to room temperature and then dropwise added to 200 ml (1.8 mol)of titanium tetrachloride maintained at 0° C., over a period of 1 hourwith stirring. After the dropwise addition was completed, thetemperature of the mixture was maintained at 0° C. for 1 hour, thenelevated to 110° C. over a period of 1 hour and 45 minutes andmaintained at the same temperature for 2 hours with stirring.

[0183] After the 2-hour reaction was completed, a solid produced wasseparated by hot filtration. The solid was sufficiently washed withhexane and decane at 110° C. until any titanium compound liberated inthe washing liquid was not detected, to obtain a hexane suspension of asolid titanium catalyst component.

[0184] The composition of the solid titanium catalyst component is setforth in Table 2.

Polymerization

[0185] Into a 1 liter autoclave was introduced 500 ml of purifiedn-heptane in an atmosphere of nitrogen. Then, 0.5 mmol oftriethylaluminum and 0.005 mmol (in terms of titanium atom) of thehexane suspension of a solid titanium catalyst component were added, andthe temperature of the system was elevated to 80° C. To the system,hydrogen was fed so that the pressure became 4.0 kg/cm²-G and thenethylene was continuously fed for 2 hours so that the total pressurebecame 8.0 kg/cm²-G. The polymerization temperature was maintained at80° C.

[0186] After the polymerization was completed, an ethylene polymerproduced was separated from the n-heptane solvent and dried.

[0187] After the drying, a powdery polymer was obtained in an yield of184.9 g. This powdery polymer had MFR of 2.8 g/10 min and an apparentbulk specific gravity of 0.33 g/cc. The results are set forth in Table3.

[0188] The particle size distribution of the powdery polymer is setforth in Table 1. TABLE 1 Parti- more less cle than 850- 500- 250- 180-100- than size 850 μm 500 μm 250 μm 180 μm 100 μm 45 μm 45 μm wt. % 0.10.3 71.1 25.8 2.1 0.6 0

Example 2

[0189] A catalyst component was prepared in the same manner as inExample 1 except that in the preparation of a catalyst component thereaction time at 110° C. was varied to 1.5 hours from 2 hours. Using thecatalyst component, polymerization was carried out in the same manner asin Example 1. The results are set forth in Table 2 and Table 3.

Example 3

[0190] A catalyst component was prepared in the same manner as inExample 1 except that in the preparation of a catalyst component thereaction temperature was varied to 105° C. from 110° C. Using thecatalyst component, polymerization was carried out in the same manner asin Example 1. The results are set forth in Table 2 and Table 3.

Example 4

[0191] A catalyst component was prepared in the same manner as inExample 1 except that in the preparation of a catalyst component theamount of decane was varied to 29.3 ml from 28.1 ml and the amount of2-ethylhexyl alcohol was varied to 15.3 g (117.5 mmol) from 16.3 g (125mmol). Using the catalyst component, polymerization was carried out inthe same manner as in Example 1. The results are set forth in Table 2and Table 3.

Example 5

[0192] A catalyst component was prepared in the same manner as inExample 1 except that in the preparation of a catalyst component theamount of decane was varied to 37.3 ml from 28.1 ml. Using the catalystcomponent, polymerization was carried out in the same manner as inExample 1. The results are set forth in Table 2 and Table 3.

Comparative Example 1 Preparation of Solid Titanium Catalyst Component

[0193] 4.76 Grams (50 mmol) of anhydrous magnesium chloride, 29.3 ml ofdecane and 15.3 g (117.5 mmol) of 2-ethylhexyl alcohol were reacted witheach other under heating at 130° C. for 3 hours, to give a homogeneoussolution. To the solution, 0.88 g (5.85 mmol) of ethyl benzoate wasadded, and they were stirred at 130° C. for 1 hour to dissolve ethylbenzoate in the solution.

[0194] The whole amount of the homogeneous solution obtained above wascooled to room temperature and then dropwise added to 200 ml (1.8 mol)of titanium tetrachloride maintained at 0° C., over a period of 1 hourwith stirring. After the dropwise addition was completed, thetemperature of the mixture was elevated to 80° C. over a period of 1hour and a half. When the temperature of the mixture reached 80° C.,2.34 g (15.6 mmol) of ethyl benzoate was added, and the resultingmixture was maintained at the same temperature for 2 hours withstirring.

[0195] After the 2-hour reaction was completed, a solid produced wasseparated by hot filtration. The solid was resuspended in 20 ml oftitanium tetrachloride and then reacted again under heating at 90° C.for 2 hours. After the reaction was completed, a solid produced wasseparated again by hot filtration. The solid was sufficiently washedwith decane at 110° C. and hexane until any titanium compound liberatedin the washing liquid was not detected, to obtain a hexane suspension ofa solid titanium catalyst component. The composition of the solidtitanium catalyst component is set forth in Table 2.

[0196] Then, polymerization was carried out in the same manner as inExample 1 except that the solid titanium catalyst component obtainedabove was used. The results are set forth in Table 3.

Comparative Example 2 Preparation of Solid Titanium Catalyst Component

[0197] 7.14 Grams (75 mmol) of anhydrous magnesium chloride, 37.5 ml ofdecane and 29.3 g (225 mmol) of 2-ethylhexyl alcohol were reacted witheach other under heating at 130° C. for 2 hours, to give a homogeneoussolution. To the solution, 1.67 g (11.3 mmol) of phthalic anhydride wasadded, and they were stirred at 130° C. for 1 hour to dissolve phthalicanhydride in the solution.

[0198] The whole amount of the homogeneous solution obtained above wascooled to room temperature and then dropwise added to 200 ml (1.8 mol)of titanium tetrachloride maintained at −20° C., over a period of 1hour. After the dropwise addition was completed, the temperature of themixture was elevated to 110° C. over a period of 4 hours and maintainedat the same temperature for 2 hours with stirring.

[0199] After the 2-hour reaction was completed, a solid produced wasseparated by hot filtration. The solid was resuspended in 200 ml oftitanium tetrachloride and then reacted again under heating at 110° C.for 2 hours. After the reaction was completed, a solid produced wasseparated again by hot filtration. The solid was sufficiently washedwith hexane and decane at 110° C. until any titanium compound liberatedin the washing liquid was not detected, to obtain a hexane suspension ofa solid titanium catalyst component. The composition of the solidtitanium catalyst component is set forth in Table 2.

[0200] Then, polymerization was carried out in the same manner as inExample 1 except that the solid titanium catalyst component obtainedabove was used. The results are set forth in Table 3.

Comparative Example 3 Preparation of Solid Titanium Catalyst Component

[0201] In a 400 ml four-necked flask, 2.86 g (30 mmol) of anhydrousmagnesium chloride was suspended in 150 ml of decane. To the suspension,8.3 g (180 mmol) of ethanol was dropwise added over a period of 1 hourwith stirring, followed by performing reaction at room temperature for 1hour. Then, 10.1 g (84 mmol) of diethylaluminum monochloride wasdropwise added at room temperature to perform reaction at 30° C. for 1hour.

[0202] Subsequently, 56.9 g (300 mmol) of titanium tetrachloride wasadded. The resulting mixture was heated and stirred at 80° C. for 3hours.

[0203] After the reaction was completed, a solid produced was separatedfrom the liquid phase. The solid was sufficiently washed with hexaneuntil any titanium compound liberated in the washing liquid was notdetected, to obtain a hexane suspension of a solid titanium catalystcomponent. The composition of the solid titanium catalyst component isset forth in Table 2.

[0204] Then, polymerization was carried out in the same manner as inExample 1 except that the solid titanium catalyst component obtainedabove was used. The results are set forth in Table 3.

Comparative Example 4

[0205] A solid titanium catalyst component was prepared in the samemanner as in Example 1 except that in the preparation of a solidtitanium catalyst component the temperature after the contact of themagnesium solution and the titanium tetrachloride (the temperatureelevated) was varied to 90° C. from 110° C.

[0206] The composition of the solid titanium catalyst component is setforth in Table 2.

[0207] Then, polymerization was carried out in the same manner as inExample 1 except that the solid titanium catalyst component obtainedabove was used.

[0208] As a result, a powdery ethylene polymer was obtained in an yieldof 76.1 g. This powdery ethylene polymer had MFR of 2.4 g/10 min and anapparent bulk specific gravity of 0.31 g/cc. The results are set forthin Table 3.

Comparative Example 5

[0209] A solid titanium catalyst component was prepared in the samemanner as in Example 1 except that the temperature after the contact ofthe magnesium solution and the titanium tetrachloride (the temperatureelevated) was varied to 120° C. from 110° C. Using the solid titaniumcatalyst component, polymerization was carried out in the same manner asin Example 1.

[0210] The results are set forth in Table 2 and Table 3.

Comparative Example 6

[0211] A catalyst component was prepared in the same manner as inExample 1 except that in the preparation of a catalyst component theamount of tetraethoxysilane was varied to 2.1 g (10 mmol) from 3.1 g (15mmol). Using the catalyst component, polymerization was carried out inthe same manner as in Example 1. The results are set forth in Table 2and Table 3.

Comparative Example 7

[0212] A catalyst component was prepared in the same manner as inExample 1 except that in the preparation of a catalyst component theamount of tetraethoxysilane was varied to 4.2 g (20 mmol) from 3.1 g (15mmol). Using the catalyst component, polymerization was carried out inthe same manner as in Example 1. The results are set forth in Table 2and Table 3.

Comparative Example 8

[0213] A catalyst component was prepared in the same manner as inExample 1 except that in the preparation of a catalyst component theamount of tetraethoxysilane was varied to 2.1 g (10 mmol) from 3.1 g (15mmol) and the temperature after the contact of the magnesium solutionand the titanium tetrachloride (the temperature elevated) was varied to90° C. from 110° C. Using the catalyst component, polymerization wascarried out in the same manner as in Example 1. The results are setforth in Table 2 and Table 3. TABLE 2 Composition of catalyst (% byweight) Ti Mg Cl Si OEt*¹ OEH*² Ex. 1 6.5 16.0 62.0 0.2 1.0 3.2 Ex. 27.1 15.0 61.0 0.2 2.4 4.0 Ex. 3 7.5 15.0 60.0 0.3 2.8 5.1 Ex. 4 6.7 15.560.0 0.2 2.0 2.7 Ex. 5 6.5 16.0 61.0 0.2 2.0 3.2 Comp. Ex. 1 3.3 17.060.0 — — 1.4 Comp. Ex. 2 2.2 19.0 60.0 — — 0.1 Comp. Ex. 3 5.1 16.0 61.0— 10.0 — Comp. Ex. 4 9.6 13.0 60.0 0.6 4.8 11.3 Comp. Ex. 5 6.0 17.065.0 0.2 ≦0.1 2.5 Comp. Ex. 6 6.7 16.0 62.0 0.1 0.5 3.2 Comp. Ex. 7 6.616.0 62.0 0.3 2.7 3.4 Comp. Ex. 8 10.1 12.0 60.0 0.2 3.0 12.0

[0214] TABLE 3 Results of polymerization Bulk specific Activity MFRgravity g-PE/g-catalyst g/10 min g/cc Ex. 1 50,100 2.8 0.33 Ex. 2 49,7002.8 0.32 Ex. 3 49,500 3.6 0.32 Ex. 4 44,800 3.1 0.29 Ex. 5 52,800 3.00.31 Comp. Ex. 1 12,000 2.1 0.35 Comp. Ex. 2  1,900 3.3 0.29 Comp. Ex. 331,900 2.5 0.34 Comp. Ex. 4 30,400 2.4 0.31 Comp. Ex. 5 31,700 2.2 0.29Comp. Ex. 6 41,100 2.8 0.34 Comp. Ex. 7 52,900 4.2 0.30 Comp. Ex. 826,200 2.9 0.30 Results of polymerization Particle size distribution (%By weight) >500 μm 100-500 μm <100 μm Ex. 1 0.4 99.0 0.6 Ex. 2 1.3 97.90.8 Ex. 3 2.6 96.5 0.9 Ex. 4 4.3 94.2 1.5 Ex. 5 2.9 95.6 1.5 Comp. Ex. 14.1 91.3 4.6 Comp. Ex. 2 1.0 91.5 7.5 Comp. Ex. 3 2.3 81.4 16.3  Comp.Ex. 4 4.0 94.8 1.3 Comp. Ex. 5 0.9 98.7 0.5 Comp. Ex. 6 2.1 96.0 1.9Comp. Ex. 7 1.0 96.4 2.7 Comp. Ex. 8 2.5 95.1 2.5

Example 6 Preparation of Solid Titanium Catalyst Component

[0215] 4.76 Grams (50 mmol) of anhydrous magnesium chloride, 28.1 ml ofdecane and 16.3 g (125 mmol) of 2-ethylhexyl alcohol were reacted witheach other under heating at 130° C. for 3 hours, to give a homogeneoussolution. To the solution, 3.1 g (15 mmol) of tetraethoxysilane wasadded, and they were stirred at 50° C. for 2 hours to dissolvetetraethoxysilane in the solution.

[0216] The whole amount of the homogeneous solution obtained above wascooled to room temperature and then dropwise added to 200 ml (1.8 mol)of titanium tetrachloride maintained at 0° C., over a period of 1 hourwith stirring. After the dropwise addition was completed, thetemperature of the mixture was maintained at 0° C. for 1 hour and thenelevated to 110° C. over a period of 1 hour and 45 minutes. When thetemperature of the mixture reached 110° C., 1.0 g (5 mmol) oftetraethoxysilane was added.

[0217] The mixture was further stirred at 110° C. for 2 hours. After the2-hour reaction was completed, a solid produced was separated by hotfiltration. The solid was sufficiently washed with hexane and decane at110° C. until any titanium compound liberated in the washing liquid wasnot detected, to obtain a hexane suspension of a solid titanium catalystcomponent. The composition of the solid titanium catalyst component isset forth in Table 4.

Polymerization

[0218] Into a 1 liter autoclave was introduced 500 ml of purifiedn-heptane in an atmosphere of nitrogen. Then, 0.5 mmol oftriethylaluminum and 0.005 mmol (in terms of titanium atom) of thehexane suspension of a solid titanium catalyst component were added, andthe temperature of the system was elevated to 80° C. To the system,hydrogen was fed so that the pressure became 4.0 kg/cm²-G and thenethylene was continuously fed for 2 hours so that the total pressurebecame 8.0 kg/cm²-G. The polymerization temperature was maintained at80° C.

[0219] After the polymerization was completed, an ethylene polymerproduced was separated from the n-heptane solvent and dried.

[0220] The results are set forth in table 5.

Example 7

[0221] A catalyst component was prepared in the same manner as inExample 6 except that the amount of tetraethoxysilane (second addition)added when the temperature reached 110° C. was varied to 2.1 g (10 mmol)from 1.0 g (5 mmol). Using the catalyst component, polymerization wascarried out in the same manner as in Example 6. The results are setforth in Table 4 and Table 5.

Comparative Example 9

[0222] A catalyst component was prepared in the same manner as inExample 7 except that the temperature elevated in the preparation of acatalyst component was varied to 120° C. from 110° C. and the secondaddition of tetraethoxysilane was carried out when the temperaturereached 120° C. Using the catalyst component, polymerization was carriedout in the same manner as in Example 7. The results are set forth inTable 4 and Table 5.

Comparative Example 10

[0223] A catalyst component was prepared in the same manner as inExample 7 except that the temperature elevated in the preparation of acatalyst component was varied to 90 ° C. from 110° C. and the secondaddition of tetraethoxysilane was carried out when the temperaturereached 90° C. Using the catalyst component, polymerization was carriedout in the same manner as in Example 7. The results are set forth inTable 4 and Table 5. TABLE 4 Composition of catalyst (% by weight) Ti MgCl Si OEt OEH Ex. 6 6.6 16.0 63.0 0.2 2.7 3.5 Ex. 7 6.6 15.0 63.0 0.33.0 3.9 Comp. Ex. 9 6.0 16.0 65.0 0.1 1.0 2.2 Comp. Ex. 10 9.8 13.0 60.00.6 5.2 12.5

[0224] TABLE 5 Results of polymerization Bulk specific Activity MFRgravity g-PE/g-catalyst g/10 min g/cc Ex. 6 52,900 4.4 0.33 Ex. 7 54,6004.0 0.32 Comp. Ex. 9 33,300 3.5 0.29 Comp. Ex. 10 32,500 3.8 0.30Results of polymerization Particle size distribution (% By weight) >500μm 100-500 μm <100 μm Ex. 6 1.0 98.6 0.5 Ex. 7 1.6 97.9 0.6 Comp. Ex. 92.9 96.5 0.6 Comp. Ex. 10 3.8 94.8 1.5

What is claimed is:
 1. A solid titanium catalyst component beingobtained by a process comprising: a step of bringing (a) a liquidmagnesium compound into contact with (b) a liquid titanium compound inthe presence of (c) an organosilicon compound having no active hydrogenin an amount of 0.25 to 0.35 mol based on 1 mol of the magnesiumcompound (a); and a step of elevating the temperature of the resultingcontact product (i) to a temperature of 105 to 115° C. and maintainingthe contact product (i) at this temperature, said solid titaniumcatalyst component comprising magnesium, titanium, halogen and theorganosilicon compound having no active hydrogen (c).
 2. A solidtitanium catalyst component being obtained by a process comprising: astep of bringing (a) a liquid magnesium compound into contact with (b) aliquid titanium compound in the presence of (c) an organosiliconcompound having no active hydrogen in an amount of 0.25 to 0.35 molbased on 1 mol of the magnesium compound (a); and a step of elevatingthe temperature of the resulting contact product (i) to maintain thecontact product (i) at a given temperature of 105 to 115° C., whereinthe organosilicon compound having no active hydrogen (c) is added in anamount of not more than 0.5 mol based on 1 mol of the magnesium compound(a) while the temperature of the contact product (i) is elevated from atemperature lower by 10° C. than the temperature maintained to atemperature at which the elevation of the temperature is completed, orafter the elevation of the temperature is completed, so as to bring thecompound (c) into contact with the contact product (i), said solidtitanium catalyst component comprising magnesium, titanium, halogen andthe organosilicon compound having no active hydrogen (c).
 3. An ethylenepolymerization catalyst comprising: [I] the solid titanium catalystcomponent as claimed in any one of claims 1 and 2, and [II] anorganometallic compound.
 4. An ethylene polymerization processcomprising polymerizing ethylene or copolymerizing ethylene and acomonomer in the presence of the catalyst as claimed in claim 3.